1. Field of Invention
The present invention pertains generally to magnetic recording and more specifically to a device for emulating a prerecorded magnetic stripe on a transaction card.
2. Description of the Background
With the advent of the use of microchips in various transaction cards such as financial transaction cards, computer access cards, security access cards, etc., a need has developed for automatically transferring information from one card to an external device. Conventional prerecorded magnetic stripes on credit cards are capable of transferring fixed information to an external device, such as a card readers, including point of sale machines and automatic teller machines, but lack the versatility of being able to provide variable information, i.e., information which may change with each use of the card. For example, it may be desirable to transmit information, such as a verification number, which changes with each use of the card, such as disclosed in U.S. patent application Ser. No. 671,748 filed Nov. 15, 1984 now U.S. Pat. No. 4,614,861 entitled A Unitary Self-Contained Card and Verification & Validation System & Method by Leonidas Pierre Pavlov and Nabil M. Abu-Jbara, and U.S. patent application Ser. No. 834,637 filed Feb. 28, 1986 entitled A Unitary Self-Contained Electronic Card and System by Leonidas Pierre Pavlov and Nabil M. Abu-Jbara. Additionally, it may also be desirable to transfer other variable information from the transaction card to the card reader such as the amount of the transaction and other transaction information. The two above-referenced patent applications are specifically incorporated herein for all that they disclose.
A pre-examination search was performed on the concept of using magnetic field generators to emulate a magnetic stripe in a transaction card such as a credit or debit card. The results of that search uncovered the following patents:
______________________________________ Patent No. Inventor Issue Date ______________________________________ U.S. Pat. No. 4,354,099 Rayment et al. Oct. 12, 1982 GB2079017A Computrol Systems, Ltd. Jan. 13, 1982 Rayment et al. U.S. Pat. No. 4,253,017 Whitehead Feb. 24, 1981 ______________________________________
U.S. Pat. No. 4,354,099 issued to Rayment et al. discloses an identifier device which interacts with a reader to identify the device. The reader generates a current on drive coil A which interacts with detector coil B to induce a current in drive coil C. The magnetic field which is generated by drive coil C in the identifier is detected by detector coil D in the sensor. Detector coils and drive coils B and C in the identifier are laid out in an array, such as illustrated in FIG. 5. Depending upon which of these coils are interconnected, a specific set of drive coils C are activated to specifically identify the identifier. The United Kingdom Patent Application No. GB2079017A discloses the same invention as disclosed in U.S. Pat. No. 4,354,099, which is the equivalent of the United Kingdom Patent Application.
U.S. Pat. No. 4,253,017 issued to Whitehead on Feb. 24, 1981 discloses a mganetically coded identification card which has a multiplicity of magnetic core spots 20 that can be alternatively recorded in opposite directions. A number of the magnetic core spots are permanently recorded while other spots can be changed to indicate variable information, such as the last port of entry, or egress, and the last use of the card. Data recorded on the magnetic spots may be erased and replaced with new data. Recording is accomplished by energizing coils on horseshoe magnets in the required manner to magnetize the spots to record the variable information.
A literature search was also performed in the Dialog database regarding magnetic structures. The following patents were uncovered in that search.
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 4,494,125 Springer Jan. 15, 1985 4,470,015 Springer Sept. 4, 1984 4,414,554 Springer Nov. 8, 1983 ______________________________________
Each of the Springer patents referenced above discloses circular magnetic generators for generating magnetic vectors having a spherical geometry which is well defined for the purpose of magnetic image storage with high resolution. The Springer patents disclose various plating techniques for forming the concentric magnetic structures.
As can been seen from the above-cited references, the practical implementation of transferring data from a card, which generates information through a microprocessor stored in the card to an external card reader has not been developed to date. The use of electrical contacts on the surface of the card suffers from many disadvantages and limitations. For example, these contacts may become dirty, worn or oxidized so that an adequate electrical connection cannot be made between the card reader and the card contacts. More importantly, precise alignment of the card to establish electrical contact with the card reader is somewhat difficult and requires modification of the vast number of currently existing card readers. It has also been found in the course of testing cards using external electrical contacts, that static electricity transmitted through the electrical contacts to the chips frequently causes failure of the chip. Consequently, such systems do not provide a reliable and rugged manner of transferring data from an electronic card to a card reader, which is necessarily required in a transaction card environment.
Other implementations, such as disclosed in the Whitehead and Rayment patents, comprise complex and expensive systems that do not provide the flexibility necessary to accomplish the desired result of easily transferring data from a card to the card reader. Each of these systems attempts to provide an array of discrete magnetic generator devices. To implement such a system with a microprocessor would require an expensive and complex multiplex system. Moreover, it is extremely desirable to have such a card system interact with the large number of presently existing card readers, as set forth above. The ability to produce a number of discrete magnetic field generators with the read density required to emulate a prerecorded magnetic stripe on currently existing transaction cards would be extremely complex and expensive to produce.
Consequently, it is desirable to provide a magnetic field generator for transferring data from the microprocessor of a transaction card to an external device such as a card reader in a manner which will allow such a system to interact with the large number of presently existing card readers.